The present invention relates to microwave devices used in medical hyperthermia and thermotherapy (referred to collectively herein as "heat therapies"), and diagnostics, and to methods of using such devices.
Localized heat therapies, i.e., hyperthermia (heating to temperatures below 45.degree. C.) and thermotherapy (heating to temperatures above 45.degree. C.), have been intensively investigated for the last two decades for many disease processes including benign prostatic hyperplasia (BPH) and neoplasms.
However, methods of delivering heat including warm fluid, focused ultrasound, radio frequency, and microwave approaches have been applied to abnormal tissue with only limited success. The prostate gland is one organ targeted as a candidate for applying heat delivery techniques. Because microwave energy can be applied without incision, this approach is one being evaluated. Furthermore, this technique advantageously can be applied in an outpatient setting.
For heat therapy to be applied safely, it is very important that the applied heat be confined to the target area (e.g., BPH tumor) alone, to avoid damaging nearby healthy tissue or organs.
Some devices for heat therapy have utilized microwave heating, for example those disclosed in U.S. Pat. Nos. 4,700,716 and 4,776,086, the disclosures of which are incorporated herein by reference. Microwave energy elevates temperature by increasing the molecular motion within cell structures. As the frequency decreases, tissue penetration increases. Small diameter microwave antenna probes have been inserted into the body through normal body passages or, on occasion, directly into diseased tissue, using hollow plastic catheters.